Millions of adult manual resuscitators are used each year in emergency situations to temporarily augment ventilation, both inside and outside of hospitals. These devices are sometimes used by personnel with limited training, as has been pointed out in the introduction to ISO8382; the International Standard that specifies the minimum performance and safety requirements for the type of resuscitator with which our spirometer is intended to be used.
Because of the limited training of some of the clinicians which may use these resuscitators, and the importance of their providing correct ventilatory parameters (tidal and minute volumes) in critical situations, we believe the use of the spirometer to be of great importance as it will give the clinician a good indication of the amount of gas the patient is actually receiving by measuring the amount of gas the patient is exhaling. However, the value of the spirometer extends beyond this and can provide valuable information to even a well-trained clinician. For example, the clinician may assume that the patient is receiving the amount of gas determined by the frequency and amount of compression applied to the bag. Under ideal conditions this is true, but particularly when the patient's lungs are non-compliant or a mucous plug is present, leakage can occur. Potential sites of leakage are around the face mask or endotracheal tube cuff, or through a pressure vent valve, at tubing connections, through a malfunctioning air inlet valve, and elsewhere. In reality, the patient may be receiving little or no ventilation. The instructions typically supplied by the manufacturers of the manual resuscitators, for the clinician to observe the rise and fall of the chest and listen for exhalation to assure proper ventilization, is often not practical, especially at prehospital emergency sites. Factors such as high background noise and difficulty in seeing chest wall movement due to rigid chest walls, obesity and bulky clothing can render these instructions meaningless. This has been frequently pointed out in the literature.
Furthermore, ISO 8382 recommends that a functional test of the resuscitator be carried out immediately prior to use. This is indeed a good idea but often overlooked when a patient needs immediate intervention to initiate respiration.